When working in C++20 I am accepting a range for my template function (really a constructor). When I specify the std::range::input_range concept for the parameter the function isn't visible and I can't use it. Reverting input_range back to typename will work, but I'd like to be able to use concepts.

When looking at the definition of CSVReader I see there are some types that aren't defined that could be causing this, such as const_iterator, const_reference, and const_pointer. There may be other issues also.

I'm working on a graph library prototype for the standard library and it would be useful to have this (paper P1709). If I have time, I might try to fork it and make some changes but I have a lot of other priorities right now.